Added second battery switch...

[IDBoating]

When I got my 24Ve, I was surprised that there was only a battery switch for the engine circuit. The accessory circuit had no battery switch, and the only way to make certain all power was completely cut off was to climb under the driver's console and flip the circuit breakers. Since you have to open the locker to turn off the engine switch, why not have a second one to handle the accessory circuit too?

Here's how things looked with a single switch:



I wanted the switches to match, so I picked up a Blue Sea model 6006 and a couple of other items:



...along with some four gauge marine rated cable and the associated ring terminals for 3/8 studs. I already had shrink wrap. I built two four gauge cables:



I then mounted the new accessory switch at the top of the locker and moved the existing engine switch up next to it. This will ease access if anyone should need to reach them with a full fat sac. The twin four gauge cables were routed over the top of the rear wall as shown.



After this last photo, I replaced a few tyraps and cleaned up the wiring harnesses in the battery compartment. I'm pretty happy with the way it turned out.

[Ewok]

Nice install! Such a great idea!

[skippabcool]

Looks good. I like your idea of zip tying all of the same battery + and - together.

[skippabcool]

Do you know how the 12V accessory plug is attached? I want to put one in each locker and wondered if I can tap into something or if I need to run wiring all the way to the accessory switch?

[ajholt7]

Very nice work.

[talltigeguy]

Isn't it usually the accessories that are accidentally left on? So it would not make much sense to not have the accessories wired into the Perko switch.

It is hard to see from the pics, but is there a single wire for the accessories? Couldn't you just run that to the Perko switch, or is there a time when you want engine power, but don't want accessory power?

[Timmy!]

Any reason you went with 4gauge on the new one and not 0 like the factory uses? I'm sure 4 gauge is fine.

[IDBoating]

It is hard to see from the pics, but is there a single wire for the accessories? Couldn't you just run that to the Perko switch, or is there a time when you want engine power, but don't want accessory power?

There were four separate wires running to the accessory battery: Two larger (6 gauge IIRC) and two smaller (8 gauge IIRC). Those were connected to one new 4 gauge cable that runs to the new switch, and a second 4 gauge cable runs from the switch to the battery.

There are two batteries, and a battery isolator, so that if the accessories stay on "too long" and drain down their battery the engine battery can still start the engine. Therefore you cannot share a single battery switch across the two circuits.

[IDBoating]

Any reason you went with 4gauge on the new one and not 0 like the factory uses? I'm sure 4 gauge is fine.

The largest existing cable running to the accessory battery was 6 gauge (IIRC). I used 4 gauge to be larger than the largest cable.

The cables running to the ENGINE's battery switch are 2/0 gauge. I didn't change anything in that circuit.

[talltigeguy]

There were four separate wires running to the accessory battery: Two larger (6 gauge IIRC) and two smaller (8 gauge IIRC). Those were connected to one new 4 gauge cable that runs to the new switch, and a second 4 gauge cable runs from the switch to the battery.

There are two batteries, and a battery isolator, so that if the accessories stay on "too long" and drain down their battery the engine battery can still start the engine. Therefore you cannot share a single battery switch across the two circuits.

I see. But if you connected them all to the single perko, it would all still be off when you shut the perko off...right?

Maybe the advantage of your approach would be you can have the engine perko switch off and leave the accessory perko on to listen to the radio and such?

[IDBoating]

I see. But if you connected them all to the single perko, it would all still be off when you shut the perko off...right?

If all power ran through a single battery switch, then all loads (engine and accessories) would be drawing from the same common power source. That would allow the accessories to drain down the batter(ies) to the point that the engine could not be started - and defeat the entire purpose of having dual isolated batteries.

Some people do wire up two batteries without an isolator. In those cases they just wire the two batteries in parallel. Same voltage, but twice the peak current and twice the amp-hour capacity. It's a simpler system, and allows the use of a single switch, but it eliminates the independence of the engine from the accessories.

EDIT: It just occurred to me that you may be thinking these battery switches are dual-pole single throw switches, i.e. "two switches controlled by a common actuator". Those may be available in this form factor, but the one in my boat is a SPST switch - one wire in, one wire out. There's no way to keep two systems isolated through a single SPST switch. Adding a second SPST switch makes it possible. Going with a DPST switch would work too, but I already had the SPST in place so I just duplicated it.

Maybe the advantage of your approach would be you can have the engine perko switch off and leave the accessory perko on to listen to the radio and such?

That is a characteristic of a multi-battery isolated system, yes. In fact, it was already possible on my boat to turn off the original battery switch and use the radio, etc. The only way to entirely disconnect the accessory battery was to flip the breakers under the driver's console. (In fact, even that may not have entirely disconnected it. There are two 8 gauge wires with inline 60A fuses that ran directly to the accessory battery. I haven't traced them out, but I suspect those run directly to the sound system amplifiers and bypass the circuit breakers.)

I wanted a fast and easy way to definitively disconnect both batteries from all loads. Giving the accessories circuit its own switch preserves the isolation between the two systems while permitting both batteries to be completely disconnected.

CAUTION: The bilge pump(s) should be hardwired to a battery through an inline fuse. The automatic operation of the bilge pump should not be defeated.

[Fiveflat]

Perko switches usually have 3 positions to isolate one battery from the other.

That solves that scenario you just gave.

[Fiveflat]

Nevermind, I see you don't have Perko, you have only a two position switch...

Here's my Perko:

[IDBoating]

Nevermind, I see you don't have Perko, you have only a two position switch...

Indeed. BTW, your switch style optionally connects battery 1, battery 2, or both... to a single common output terminal. That's not the same as a DPST switch, which has two entirely separate circuits controlled by a common knob.

They do make DPST switches (I looked it up, Blue Sea makes one in this same product line) that would allow two batteries to power the engine and accessories separately. However, as noted above, I already had the engine switch in place. And it is nice to be able to switch the two systems independently.

Thanks!

[Fiveflat]

As long as you are happy with your work, that's all that matters.

You did a fine job, it looks great.